Coupling of river discharges and alpine glaciers in arid Central Asia

Water resource is the primary factor impacting socio-economic development and security in arid Central Asia where high water stress occurs. Therefore, understanding the mechanism of water resource, particularly its associations with global warming, has unique importance for regional sustainable development. However, the dynamics of water resource is far from constrained in arid Central Asia indicated by the observed heterogenous trends of both alpine glaciers in high mountains (water tower) and river runoffs (dominant freshwater sources). Both meltwater and precipitations have been assumed to be the major contribution to the river runoff. Here, we make a systematic analysis on the 10Be exposure ages of the moraines in the high mountains and river terraces across Central Asia (n = 1057) to characterize the past changes of alpine glaciers and river discharges. The results show that the high river discharges are coupled with the alpine glacier expansions on both orbital and millennial scales, indicating a dominant contribution of meltwater to the freshwater supply. Both high river discharges and alpine glacier expansions occurred during the cold periods of the past 130 ka in Central Asia, indicating relatively low water stress under low-temperature conditions. This characteristic suggests that the water stress would in-crease with the decrease in both water reservoir and river discharges, and thus the environment would become drying with global warming in Central Asia.